(1) Field of the Invention
The present invention relates generally to fabric formation and, more particularly, to a method for high speed three-dimensional woven fabric formation of structures including three substantially orthogonal yarn systems and a machine that incorporates this method.
(2) Description of the Prior Art
In general, it is known in the art to manufacture multi-layer fabrics, including three-dimensional woven fabrics, particularly for use in aerospace and industrial applications and for use in resin-infused composite structures incorporating the same. Additionally, it is known in the art to use specialized machines for making three-dimensional woven fabrics, particularly incorporating high performance fibers to improve the characteristics of the overall woven structure.
However, overall, these prior art methods and related machines are not capable of producing three-dimensional woven fabric at high speeds. While traditional weaving machines can provide high speed weaving and fabric production, these machines are not capable of providing true three-dimensional fabric structures. Typical speeds for two-dimensional weaving machines, specifically for rapier machines, are between about 200 picks per minute to about 350 picks per minute. However, these machines are only capable of producing standard two-dimensional fabrics or "crammed" fabrics that have some additional picks or filling yarns. In the case of "cramming," additional picks are inserted during a single phase of harness action such that instead of inserting a single pick during a single phase, an extra pick or so is added. Moreover, "cramming" fabric is not used for large fabric dimensions; rather, it is used primarily as a border for towels and handkerchiefs. One significant problem with "crammed" fabric is a substantial lack of stability and control within the fabric due to the addition of picks without providing a warp or other angular interlocking of the picks. Uncontrolled shrinkage and wrinkling are prevalent in areas where "crammed" fabric is used. Thus, neither the two-dimensional fabrics nor the "crammed" fabrics that can be produced from a traditional two dimensional weaving machine at high speeds can provide adequate fabric characteristics to match those of true three-dimensional fabric structures.
While prior art three-dimensional weaving machines are capable of providing true three-dimensional fabric structures, including complex-shaped structures, the machine speeds are very slow. Typical speeds for specialized three-dimensional weaving machines are about 30 insertions per minute. Also, prior art 3-dimensional weaving machines require simultaneous stack filling insertion and continuously filing yarns. Therefore, no prior art has been capable of providing a high speed means for manufacturing true three-dimensional woven fabrics having three substantially orthogonal yarn systems. Thus, there remains a need for a method and machine for producing three-dimensional woven fabrics at reasonably high speeds. Furthermore, no prior art provides a high speed method or machine for forming three-dimensional fabric structures having a range of dimensions. Thus, there remains a need for a high speed method and machine for making three-dimensional woven fabric in a range of dimensions.